问题
I have data as follows:
library(data.table)
DT <- structure(list(State_Ab = c("VA", "VA", "VA", "VA", "VA", "VA",
"VA", "VA", "VA", "VA", "VA", "VA", "VA", "VA", "VA", "VA", "VA",
"VA", "VA", "VA", "VA", "VA", "VA", "VA", "VA", "VA", "VA", "VA",
"VA", "VA", "VA", "VA", "VA", "VA", "VA", "VA", "VA", "VA", "VA",
"VA", "VA", "VA", "VA", "VA", "VA", "VA"), year = c(1995, 1995,
1995, 1995, 1999, 1999, 1999, 1999, 2001, 2001, 2001, 2001, 2005,
2005, 2005, 2005, 2007, 2007, 2007, 2007, 2011, 2011, 2011, 2011,
2017, 2017, 2017, 2005, 2005, 2005, 2005, 2017, 2017, 2017, 1995,
1995, 1995, 1995, 2001, 2001, 2001, 2001, 2007, 2007, 2007, 2007
), County = c("Bedford", "Fairfax", "Bedford", "Fairfax", "Bedford",
"Fairfax", "Bedford", "Fairfax", "Bedford", "Bedford", "Fairfax",
"Fairfax", "Bedford", "Bedford", "Fairfax", "Fairfax", "Bedford",
"Bedford", "Fairfax", "Fairfax", "Bedford", "Bedford", "Fairfax",
"Fairfax", "Bedford", "Fairfax", "Fairfax", "Bedford", "Bedford",
"Fairfax", "Fairfax", "Bedford", "Fairfax", "Fairfax", "Fairfax",
"Fairfax", "Bedford", "Bedford", "Bedford", "Fairfax", "Bedford",
"Fairfax", "Bedford", "Fairfax", "Bedford", "Fairfax"), Type = c("B",
"B", "B", "B", "B", "B", "B", "B", "B", "B", "B", "B", "B", "B",
"B", "B", "B", "B", "B", "B", "B", "B", "B", "B", "B", "B", "B",
"A", "A", "A", "A", "A", "A", "A", "C", "C", "C", "C", "C", "C",
"C", "C", "C", "C", "C", "C"), Population = c(15528, 297214,
2053, 7505, 8963, 199282, 829, 4299, 20040, 2018, 9095, 392987,
26930, 2319, 10225, 448078, 24499, 1935, 8048, 340397, 24012,
1926, 7112, 303379, 41681, 479086, 9552, 31404, 2542, 10546,
461379, 42525, 551183, 12028, 303203, 7600, 2160, 17988, 25284,
410475, 2379, 9462, 25122, 342998, 1940, 8096)), row.names = c(NA,
-46L), class = c("data.table", "data.frame"))
Some of these values are for Bedford City, some for Bedford County. Based on the information I have, the min value should be Bedford City, the max value Bedford County. I thought I would do the following, but it fails somehow. I would like to do the following, based on Ronak's answer :
DT[County=="Bedford" & order(Population), County := c("Bedford County", "Bedford City"), .(State_Ab, year, County, Type)]
But I am getting the error:
Error in `[.data.table`(DT, County == "Bedford" & order(Population), `:=`(County, :
Supplied 2 items to be assigned to group 1 of size 4 in column 'County'. The RHS length must either be 1 (single values are ok) or match the LHS length exactly. If you wish to 'recycle' the RHS please use rep() explicitly to make this intent clear to readers of your code.
The output then becomes:
State_Ab year County Type Population
1: VA 2017 Bedford B 41681
2: VA 2005 Bedford A 31404
3: VA 2005 Bedford A 2542
4: VA 2017 Bedford A 42525
5: VA 1995 Bedford C 2160
6: VA 1995 Bedford C 17988
7: VA 2001 Bedford C 25284
8: VA 2001 Bedford C 2379
9: VA 2007 Bedford C 25122
10: VA 2007 Bedford C 1940
11: VA 1995 Bedford City B 2053
12: VA 1999 Bedford City B 829
13: VA 2001 Bedford City B 2018
14: VA 2005 Bedford City B 2319
15: VA 2007 Bedford City B 1935
16: VA 2011 Bedford City B 1926
17: VA 1995 Bedford County B 15528
18: VA 1999 Bedford County B 8963
19: VA 2001 Bedford County B 20040
20: VA 2005 Bedford County B 26930
21: VA 2007 Bedford County B 24499
22: VA 2011 Bedford County B 24012
I do not really understand where this issue is coming from..
When try the other county in the data-set, I do:
DT[County=="Fairfax" & order(Population), County := c("Fairfax County", "Fairfax City"), .(State_Ab, year, County, Type)]
I get no error, but the output is wrong (Fairfax County is MUCH larger than Fairfax City, but it not always is in the data):
23: VA 1995 Fairfax City B 7505
24: VA 1999 Fairfax City B 4299
25: VA 2001 Fairfax City B 392987
26: VA 2005 Fairfax City B 448078
27: VA 2007 Fairfax City B 340397
28: VA 2011 Fairfax City B 303379
29: VA 2017 Fairfax City B 9552
30: VA 2005 Fairfax City A 461379
31: VA 2017 Fairfax City A 12028
32: VA 1995 Fairfax City C 7600
33: VA 2001 Fairfax City C 9462
34: VA 2007 Fairfax City C 8096
35: VA 1995 Fairfax County B 297214
36: VA 1999 Fairfax County B 199282
37: VA 2001 Fairfax County B 9095
38: VA 2005 Fairfax County B 10225
39: VA 2007 Fairfax County B 8048
40: VA 2011 Fairfax County B 7112
41: VA 2017 Fairfax County B 479086
42: VA 2005 Fairfax County A 10546
43: VA 2017 Fairfax County A 551183
44: VA 1995 Fairfax County C 303203
45: VA 2001 Fairfax County C 410475
46: VA 2007 Fairfax County C 342998
This is driving me absolutely nuts.. What is going on here?
Desired result:
23: VA 1995 Fairfax City B 7505
24: VA 1999 Fairfax City B 4299
25: VA 2001 Fairfax County B 392987
26: VA 2005 Fairfax County B 448078
27: VA 2007 Fairfax County B 340397
28: VA 2011 Fairfax County B 303379
29: VA 2017 Fairfax City B 9552
30: VA 2005 Fairfax County A 461379
31: VA 2017 Fairfax City A 12028
32: VA 1995 Fairfax City C 7600
33: VA 2001 Fairfax City C 9462
34: VA 2007 Fairfax City C 8096
35: VA 1995 Fairfax County B 297214
36: VA 1999 Fairfax County B 199282
37: VA 2001 Fairfax City B 9095
38: VA 2005 Fairfax City B 10225
39: VA 2007 Fairfax City B 8048
40: VA 2011 Fairfax City B 7112
41: VA 2017 Fairfax County B 479086
42: VA 2005 Fairfax City A 10546
43: VA 2017 Fairfax County A 551183
44: VA 1995 Fairfax County C 303203
45: VA 2001 Fairfax County C 410475
46: VA 2007 Fairfax County C 342998
回答1:
I am using an function to order County and Population, and then change the County accordingly.
I noticed that VA 2017 Bedford A has only one entry for that year.
fn2 <- function(County, Population) {
if (length(County) == 1) {
return(list(County, Population))
} else {
list(County = paste(County, c("City", "County")),
Population = sort(Population))
}
}
DT[County == "Bedford", c("County", "Population") := fn2(County, Population),
.(State_Ab, year, Type)]
part of DT State_Ab year County Type Population 1: VA 1995 Bedford City B 2053 2: VA 1995 Fairfax B 297214 3: VA 1995 Bedford County B 15528 4: VA 1995 Fairfax B 7505 5: VA 1999 Bedford City B 829 6: VA 1999 Fairfax B 199282 7: VA 1999 Bedford County B 8963 8: VA 1999 Fairfax B 4299 9: VA 2001 Bedford City B 2018 10: VA 2001 Bedford County B 20040 11: VA 2001 Fairfax B 9095 12: VA 2001 Fairfax B 392987
来源：https://stackoverflow.com/questions/65339822/renaming-a-column-entry-when-it-is-the-maximum-value-by-group-gives-inconsiste